Researchers study black holes to measure photon mass

Sep 25, 2012 by Edwin Smith
Schematic illustration of the 'black hole bomb' effect. A wave thrown at a black hole can be magnified upon reflection, extracting rotational energy and spinning down the black hole. The mass of the particle acts like a 'wall' for outgoing waves (represented by the enclosing sphere in this figure), so the reflection/amplification process is repeated and causes an instability. Credit: Ana Sousa.

(Phys.org)—A global team of scientists, including a University of Mississippi physicist, has determined the best constraint on the mass of photons so far, using observations of super-massive black holes.

The research findings appear in the September issue of , one of the most prestigious, peer-reviewed academic journals in the field. "Black hole bombs and photon mass bounds" is co-authored by Emanuele Berti, UM assistant professor of physics and astronomy, along with fellow researchers Paolo Pani, Vitor Cardoso, Leonardo Gualtieri and Akihiro Ishibashi.

This paper details how the scientists, who work in Portugal, Italy, Japan and the U.S., found a way to use astrophysical observations to test a fundamental aspect of the Standard Model – namely, that photons have no mass – better than anyone before.

This video is not supported by your browser at this time.
A numerical simulation of the ‘black hole bomb’ effect for massive photons: The different colors represent different amplitudes of the reflected wave. The simulation follows the reflection/amplification process for a few cycles. Animation by Helvi Witek.

"The test works like this: if photons had a mass, they would trigger an instability that would spin down all in the universe," Berti said. "But astronomers tell us that the gigantic, super-massive black holes at galactic centers are spinning, so this instability cannot be too strong.

"The mass of the photon, if it has a mass at all, must be extremely tiny."

"Ultralight with nonzero mass would produce a 'black hole bomb': a strong instability that would extract energy from the black hole very quickly," said Pani, the paper's lead author. "The very existence of such particles is constrained by the observation of spinning black holes. With this technique, we have succeeded in constraining the mass of the photon to unprecedented levels: the mass must be one hundred billion of billions times smaller than the present constraint on the , which is about two electron-volts."

The results of this study can be used to investigate the existence of new particles, such as those possibly contributing to the dark matter that is the subject of a search using the at in Geneva. CERN is the site where the breakthrough discovery of the Higgs boson was reported earlier this year.

"That discovery filled one of the most important gaps in our understanding of the standard model of particle physics, because it explains how particles get their mass," Gualtieri said. "However, not all particles have mass. Physics makes progress by testing every nook and cranny of our commonly accepted theories. So, if we believe that a particle has no , we'd better test this idea with precise experiments.

"Observations of super-massive black holes may provide new insights which are not accessible in laboratory experiments. This would certainly be exciting. Perhaps these new frontiers in astrophysics will give us a clearer understanding of the microscopic universe."

"Paolo, Vitor, Leonardo and I are all part of an IRSES Network on 'Numerical Relativity and High-Energy Physics' funded by the European Union," Berti said. "Paolo presented a talk on this work at the first meeting of our network that was held in Aveiro, Portugal in July. This network will be used in the next four years to strengthen our collaboration even further."

Explore further: What is Nothing?

More information: To view the team's PRL paper before publication, go to arxiv.org/abs/arXiv:1209.0465 or arxiv.org/abs/arXiv:1209.0773/.

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avafeas
4.7 / 5 (12) Sep 25, 2012
The lateral thinking required to come up with a practical way to measure a photon's mass using such a macro-scale object completely blows my mind. Reading this article invigorates my interest in astrophysics.
julianpenrod
1.4 / 5 (11) Sep 25, 2012
In other words, "science" is admitting that it doesn't have utter faith in "relativity"!
Remember, the essence of light, what allows it to move at the speed it does and also have the quality of having the same velocity with respect to all observers, is that photons have zero mass! This is not a conclusion based on laboratory measurements, it is an outgrowth of the fundamental claimed precepts of "relativity" itself! It is absolutely inconsistent with "relativity" for photons to have even one billionth of one billonth the mass of neutrinos. Shills might try to suggest that, if photon masses are extremely small, they migyht be able to "slip by" the rules, but, then, particles that are billions of times bigger could be viewed as just a billion photons together, which still would require that all matter not be bound by relativity!
Lurker2358
1.7 / 5 (6) Sep 25, 2012
This si pretty stupid anyway.

In order to make a black hole "spin down" via mass transfer you'd need to hit it with a SIGNIFICANT fraction of it's own mass from a direction orthogonal to it's accretion disk, or else rotating contrary to it's accretion disk.

to do that using only "massive" photons of vanishingly small mass?

Wow. that probably takes all the photons ever made in a galaxy, even if they did have mass.
ValeriaT
1 / 5 (4) Sep 25, 2012
: if photons had a mass, they would trigger an instability that would spin down all black holes in the universe
Which mass? Rest mass or dynamic mass? And how the photons are supposed to trigger the instability of black holes? The general relativity has nothing to say about photons, about rest mass of photons the less, as the photon is concept of quantum mechanics. And the quantum mechanics cannot say nothing about black holes. In quantum mechanics all objects should explode into infinity - this theory has even nothing to say about gravity. So you cannot derive nothing about connection of photon and black holes with any contemporary theory based on quantum mechanics and/or general relativity. And even if yes - it would be a physical, if not mathematical nonsense. In general relativity the mass of photon is always zero, because it doesn't distinguish the light wave and photon concepts. This is simply how the rules of contemporary physics are set.
RealityCheck
1 / 5 (4) Sep 25, 2012
It never fails to disappoint me, the way modern 'physicists' sometimes 'want it both ways' and don't even realize they are doing it when 'interpreting' according to what they want and conveniently ignore "elephants in the room". The researchers here first say they are assured that the black hole spins, and then they want to 'simulate' a 'light bomb' scenario as if it is plausible given that spin.

Consider: IF a black hole IS spinning, then FRAME DRAGGING (ie, Lens-Thirring effect) effect in vicinity of event horizon must be HUGE.

Incoming energy/matter (photon, neutrino, electron, proton etc) will be put into an IN-SPIRALING trajectory passing through horizon in a tangential manner within 'streamlines' of energy-matter 'grazing' the horizon vicinity as it 'spirals' around and through it rather than 'bombing' it.

Did they include this factor? If they did not, then the exercise/simulation is invalid. Can't have it both ways.

PLease correct me if I missed where they did. Cheers. :)
Lurker2358
1 / 5 (2) Sep 25, 2012
Reality check:

Head on collisions can still happen in black holes, and are more likely than the big "death spiral" image you always see in a photo.

there is frame dragging and tidal forces, at least according to prevailing theory, but it's not going to stop a black hole spinning.

Also, matter can collide with a black hole from a direction that has retrograde angular momentum, and that would slow it's spin as well, while conserving total angular momentum.

Also, it has been proven that all trajectories tangent to a black hole's event horizon will fall into the event horizon, the reason for this is escape velocity assumes a tangent vector from a surface, and the black hole's escape velocity is the speed of light at the surface of the event horison.

Therefore all tangential courses fall inward anyway.

Even if you magically started with a ray of light on a point and had a tangent vector from the EH, it would fall back in.
vacuum-mechanics
1 / 5 (4) Sep 25, 2012
This paper details how the scientists, who work in Portugal, Italy, Japan and the U.S., found a way to use astrophysical observations to test a fundamental aspect of the Standard Model – namely, that photons have no mass – better than anyone before…


By the way, it is interesting to note that conventionally we still do not understand why photons have no mass, but have energy!
Actually photon does have mass, but it was treated as energy in conventional physics! The reason behind is because it is the mass of part of the vibrating medium which acts as the carrier of light wave packet (photon). This is why it was said that light cannot stop, because if it stops, then there is no light (i.e. no vibration part of medium), detail could be found below.
http://www.vacuum...21〈=en
Nanowill
1 / 5 (3) Sep 26, 2012
First you have to understand mass. Newton invented the notion of mass to explain gravity, which presumably results from metric distortion caused by EM energy localizing to form a particle. A photon can only have a transient two dimensional distortion, i.e. metric curvature. So how do you want to define mass, 2D or 3D metric curvature? The idea of photon mass is silly unless mass is defined first. This is the same issue as defining a particle, 3D localized EM energy or not? Does 2D EM energy localization qualify as a "particle"?. If you don't define terms its just gobblygook.
DavidW
1 / 5 (2) Sep 26, 2012
Seems to me this video could be used for quick hypnosis.
Benni
1 / 5 (4) Sep 26, 2012
All energy (the electro-magnetic spectrum) at any frequency propagates at a speed of 186,284 mile/sec, speed of light (photons) if you will. All energy that has ever been created was created when mass was transformed to energy, this is the only way energy is created.

When a given mass is transformed to energy, the given mass becomes lighter. It becomes lighter because photons (energy) carries away mass & takes a proportionate share of gravity with it.

Photons (energy)do not have "rest mass" as particles do, because they cannot exist below the speed of light, so, photons are assigned "rest mass equivalence", meaning they have actual mass but not at zero inertia because photons (energy) cannot exist at zero inertia.

I learned this in engineering school from a nuclear physics course in preparation for my next course in the design of nuclear reactors.
Nanowill
1.8 / 5 (5) Sep 26, 2012
There is no such thing as "mass" in the same sense there is no such thing as "color". Color is just the observer's perception of specific EM wavelengths, i.e. only the wavelengths exist not the color. Mass is an observer perception arising from the existence of gravity, which is caused by the curved metric required to localize EM energy and form a particle, i.e. only the EM energy and the curved metric exists. Mass does NOT create gravity. The boundary (surface) of a curved metric that localizes EM energy as a particle is orthogonal in two dimensions to all radials that project into the observer domain, i.e. the boundary is c^2 remote from the observer domain and the EM energy thus appears as E/c^2 = mass. A photon moving at c in matter free space does not have a closed boundary, so cannot have mass in the same sense as particles. The idea of mass is just a convenient notion in the same sense color is just a convenient notion. All 'm' for mass in physics could be replaced by E/c^2.
Fleetfoot
not rated yet Sep 27, 2012
Which mass? Rest mass or dynamic mass?


Invariant mass of course.
Fleetfoot
not rated yet Sep 27, 2012
In other words, "science" is admitting that it doesn't have utter faith in "relativity"!
Remember, the essence of light, what allows it to move at the speed it does and also have the quality of having the same velocity with respect to all observers, is that photons have zero mass! This is not a conclusion based on laboratory measurements, it is an outgrowth of the fundamental claimed precepts of "relativity" itself! It is absolutely inconsistent with "relativity" for photons to have even one billionth of one billonth the mass of neutrinos.


Relativity applies to particles with either zero or non-zero mass. If it turned out that photons had a tiny mass, relativity would just treat them the same way as neutrinos.
Benni
2 / 5 (4) Sep 28, 2012
Now, for a photon, this is zero since E = pc.


Wrong, for a photon it is E=mc^2

I'll give you the best example there is that photons carry "realtime mass" to coin a phrase. Everyday you look around you & see the product of it, you partake of it when you eat.

The process of photo-synthesis is the direct transformation of energy into mass. This can't happen if energy has zero mass with zero gravity. I learned this in the nuclear physics that was a pre-requisite course for nuclear reactor design.
ValeriaT
1.5 / 5 (4) Sep 29, 2012
The process of photo-synthesis is the direct transformation of energy into mass
It isn't - the plants gain their mass from carbon dioxide. The invariant mass of photons which single plant absorbs during its life is in order of attograms. These plants grow virtually from air... And they can grow so even at zero gravity conditions.
antialias_physorg
not rated yet Oct 01, 2012
The process of photo-synthesis is the direct transformation of energy into mass.


This goes for any chemical (and nuclear) reaction.
E.g. in an exothermic reaction (where photons and phonons are emitted) the sum of the end products will weigh less than the sum of the reactants.
E.g. in nuclear gamma decay (decay in which only photons are emitted) the substance loses mass over time.

The mass gained/lost is very small. But it is that mass/energy conversion which drives all life (note that the BUILDING of additional plant/animal matter is done by incorporating external atoms. However BUILDING stuff is not the same as RUNNING stuff. The building itself may require energy, which in turn is implicitly garnered from mass conversion (i.e. chemical reactions in our bodies))